Blower impeller



Jan. 2, 1945.` J. FLLEMANN 2,366i251 i BLOWER IMPELLER .original Filed Dec. iv, 1940 2 sheets-sheet 1 grime/who@ l Jan. 2, 1945.. J, FLLEMANN 2,366,251

BLOWER IMPELLER original Filed Deo. 17, 1940 2 sheets-sheet 2 I -cfaa/Wzjzlema UNITED STAT application is a division @of Patented Jan. 2,` `1945 Es PATENT OFFICE l "BLOWER IMBELLEB, h h l h `Johann"Iiillemann,Washington,` D. C., h original application December 17;1946Qseria1 t .No.*370,553. Divided and thsapplication May 13, 1943, SerialNo.318.6,887` I w my pending application, seria; No.` `370,553,16r Blowen im- "filed'Decernber 1'7J 1940.

`pellers and methods of manufacturing saine,

This invention `relates to improvements in cen- ,.-trifugal gasblowers, and more particularly to impellers of` thelclosed type, of a construction which is particularly adaptable for being prof,}.ducedby die-shaping, `that is, die-casting or drop-forging. By` closed type impellers` is meant impellers in `which the` generally radially` `disposed blciwervanes are disposed `between a pair, of disc-,like plates` at `their sides so that the `gas passages` 4formed by thevanes andlplates h andwhichextend ingenerally radial directions i V,Theclosed type of inflpellers` is` recognized as h @eine more "fopenff type` impellers, that is, the type having at are open only at their Ainner and outer ends.-

h efficient aerodynamically l than leastoneside oftheair passages open;` but, :on

` theother hand, the` closed type of impeller has h their adoption.

i presented certain manufacturing problems and difliculties which have Vto, some `extent `retarded It has been proposedto make ,impellers of the "lclosed type `by `casting in `one piecemand, with ""lcertain renementsiof construction', thissystem offrnanufactufre has provedsuccessful, but ordinary casting operations involve comparatively @greater labor and time, and for quantity productailedjdescription of the method andthe accom- "Danying drawings whichfillustrate an fernbedi- `Inthedrawings:` `Fig.-11is an axial Vsectional v rI I of Fig. 2 of a centrifugalblower` havinga y ment of the inventionf View on the line closed type impellercomposed primarily cf` two l, diefshaped parts joined together; Fig. 2 is a sectional View of the impelleron the line II-II of Fig. 1 illustrating the cross-'secticnn l alshape of the vanes; and l r I impelleron the line III-III of Fig. 1. H

i Fig. 3:isacross-{sectionalview of part of the y I In Fig. 1` of the drawingsa centrifugal blower casing is designated by numeral I. The casing may be of the general shape" of a volute and is providedl with a gas` inlet opening 2 at one side and ancpening 3iforlthelimpeller `drvelshaft 4 `at theCother side.l The impeller hub 6 is mounted `on the drive shaftf. i This hub forms the cenh tral` `portion :of one main ,part` of` `the impeller whichcomprises, in addition to the hub,a plate l `lextendingoutwardly andparts` 8 of the vanes i 9v extending approximately at right angles to said platel` ,h l h, h h "f Theother main part `IIJ ofthe impeller comprises,` a` ring-shapedplate I I having a central openingmIZ and other parts I3 of` impeller vanes tion"` it ismore desirable` to `i-lnd structuresiin` 1 `which `drop-forging `or die-casting can be` `used in `place of ordinary casting. h `The present `invention hasfor `an `objectto provide a closed type impeller adapted to `be produced in two principal parts by permanent mold "operations, that is, by die-shaping, such as dropforging or `die-casting, operations and, `which parts can then be readily broughtinto condition to be eiectively joined together intoanassemn bled impeller. l

A further object bf this invention is to provide aclosed type impeller in which two parts produced by die-shaping operations are assembled with locking shoulders adapted to transmit the centrifugal forces therebetweenand held to-` gether in engaging relation by securing means extending through the blades and through `the side plates.

Another object of this invention is to provide a` h closed type impeller having vanes of fluid foil cross-sectional shape, considered in a plane h transverse to the axis of rotation.

h Further objects and` advantages of the inven- `tion will be apparent from the following deouter ends thereof are open. The impeller is therefore ofthe closed type.

corresponding` in position `and `registering with the respectively corresponding parts 8` of vanes h 9.` `It is apparent from Fig. 1 that the plates `I `anc'LII `cldse the `sides of the gas passages I4` betweenthe vanes so that'only the inner and t n Fromnig. 1 win also be seen thatthe two parts 8, and n I3 of .the impeller vanes have engaging `shoulders IB and` I'l` which resist the tendency of the partHIU ofthe impellerto be distorted outwardly `under the strong influence oit'` centrifugal i force,4 at high speed. `The two parts of` the `impeller are held together in locking` engagement `where the vanes are of comparatively greater thickness.

by securing means which may comprise bolts or rivets I8 which pass through openings I9 in the plates and vanes at radially intermediate points At the Vpoints where the rivets pass l h-through the plates 'I and l I`4 the plates are `of in-` creased thickness in order to'be better able to` carry the stress applied by `the rivets. This thickening is conveniently obtained by providing a ring-like flange or rim `I5 on plate 'lhaving a shoulder surface which cooperates with a labyrinth packing 21, which seals between plate 1 and basing I, and the thick portion 20 `of plate jII` also has a shoulder which cooperates with another packing 28.

In order that the vanes shall have sui'icient thickness to accommodate the bolts and to resist the strong centrifugal forces without greatly reducing the aerodynamic efficiency of the impeller or causing undesirable whistling noise in operation, thevanesare given fluid foil shape in the direction offlow of the gasill This uid foil cross-sectional shape is clearly apparent from Fig. 2 of the drawings, from which it can be seen that the inner and outer edges of the vanes are comparatively thin and rounded off while' the central parts are thicker and of suflicient thickness to allow the rivets I8 to pass therethrough. The surfaces of the rounded-olf. innenand. outer edges pass over smoothly to' the' surfaces or. the central parts so as to avoid impairment of aerodynamic eiciency and minimize noise in opera-l tion.

Another feature of: the shape of the` vanes is that their thickness isprogressively greaterffrom the centers toward their lateral vedges, asis apparent from Fig. 3. The most importantpurpose of this feature is to providerthe'necessary draft to enable removal ofi'thevanes from the dies in their production by die-shaping'operatons.

The present construction is .particularly well adapted `for production Vof iimpellers intlarge iquantities, that is,I 'suchlqu'antities as would be re-f.

quired for small-size*,impellersfforuse in turbochargers or superch'argingcomparatively small internal .combustion engines. By reason ofthe f' smooth'surfaces obtained byy die-shaping operations,v compared -withthe rough `surfaces obtainedby ordinary sand'casting methods the provision of a constructionwhich is adaptable'for die-shaping is of extreme importance This eliminates a large amount of finishing and polishing after the `casting operation, while at the same :time pro-- viding impeller "vanes which areU suliciently smooth to givegood aerodynamic efliciency.

Compared with other constructions, the presenty construction has the'advantage of greatv simplicity and speed of production, yet gives impellers of great strength and dependability Without material sacrifice in elli'ciency over impellers made according to other constructions andwby more laborious and time-consuming methods.

I claim:

l. An' impeller of the closed type for rotary centrifugal "gas blowers comprising a 'pair of `plates each having a plurality of blower vane parts formed on a side wall thereof, said vane parts being located on 'said'plates in registering pairs, the corresponding surfaces thereof fitting together exactly and having interengaging shoulders facing inwardly and outwardly respectively for transfer of radial forces, said plates and vanes having openings extending vtherethrough substantially in the'direction ofthe axis of rotation of the impeller, and securing means extending Kthrough said openings.

2. In a centrifugal blower, a casing, a rotary impeller of the closed type, said impeller comprising a pair of plates `each having parts of impeller vanes ,formed on one side in position to register with corresponding vane parts of the other plate,

the corresponding vane parts tting together exactly, the sides of the gas passages formed between the vanes being closed by said. plates and 1 Lone of said plates havingia :central opening serv- 10 ing as an inlet for gas to said passages, said plates having circularly extending portions of greater thickness than their normal thickness extending raround said plates at positions opposite the midvdle. portions of the vane parts, the middle portions of's'aid vanes and said thicker portions of f .saidplates being `provided with openings extendv"wing in the general direction of the axis of rota-- Ytion of the impeller, and securing means extendy ingthrough s'aid openings, said thicker portions feo of said plates having cylindrical outer surfaces f and llabyrnthfpackings engaging said cylindrical lsurfaces and the casing and sealingthere'betwe'en. i

31An impeller of the closed type frjrotaly centrifugal blowers comprising -a pair of plates g5 each having parts'of impellervanes' formed on one side inA position to register with' corresponding vanefparts of the' other plate,-thecorresponding `vane parts `fitting'together exactly, thesides of the gaspassages formed'betweenthe vanesbeing ao closed by said plates and one of said plates 'havring a central opening serving as an inlet'rforqigas to said passages, some ofthe corresponding vane parts 'having registering openingsY :extending I therethrough and through 'the plates inthe 'di- 35 rection of the axis of rotation of 'the impeller,

and securing means extending through said openings, said vane parts being thicker at the" lateral ends adjacent the plates than at the centers and being thicker at their -radially intermediate por- 4o tions than toward` their inner and outerjedges.

4. An impeller of vthe closedtype for'rotary centrifugal blowers comprisinga pairof .plates each having parts of impeller vanes'forrne'diton one sidein position to register with correspond-` ing vane parts of the other plate, the corresponding'vane parts fitting together exactly, thesides of the gas passages formed between the vanes being closed by said plates and one of said plates having a central opening serving asaninletfor 50 gas to said passages, and means for securingthe to JOHANN V'rsu'univr-hina. 

